maskflow-evidence

A metadata-only, verifiable record of what MaskFlow masked — never the values themselves. Publishing the schema and shipping the emitters in the open lets any user confirm, by reading the code, exactly what leaves their environment.

Part of MaskFlow. MIT, free forever, no telemetry.

What an event looks like

{"event_id":"…","ts":"2026-09-07T12:00:00Z","session_id":"…","service":"support-bot",
 "environment":"prod","entity_type":"AADHAAR","count":1,"score":0.98,
 "recognizer":"pattern:AADHAAR","action":"masked","provider":"openai","model":"gpt-4o",
 "pack_version":"0.5.0","engine_version":"0.6.0"}

There is no field that can carry free text. Every string is a bounded slug; there is no place for a detected value, a placeholder, or the mapping between them. This is enforced structurally in schema.py and in CI by tests/test_schema_metadata_only.py.

Off by default

Nothing is emitted unless you turn it on. In .maskflowrc:

[evidence]
enabled     = true
sink        = "file"          # stdout | file | syslog | webhook | otlp
path        = "evidence.log"
service     = "support-bot"
environment = "prod"

The gateway reads MASKFLOW_GATEWAY_EVIDENCE_* environment variables with the same names.

Sinks

What is deliberately not collected

Raw values, masked values, the mapping, request/response bodies, prompt text, and any user identifier beyond a caller-supplied opaque session_id. See docs/evidence.md for the full statement.